Estimated resident population (ERP) is the official measure of population in Australia. The concept links people to a place of usual residence within Australia. Usual residence is that place where each person has lived or intends to live for six months or more in a reference year.

Estimated resident population estimates include usual residents who are overseas for less than 12 months. It excludes overseas visitors who are in Australia for less than 12 months and foreign diplomatic personnel and their families.

Estimated resident population estimates are obtained by adding to the estimated population at the beginning of each period the components of natural increase (on a usual residence basis), net overseas migration and, for the States and Territories, interstate movement involving a change of usual residence.

After each census, estimates for the preceding intercensal period are revised by incorporating an additional adjustment (intercensal discrepancy) to ensure that the total intercensal increase agrees with the difference between the estimated resident populations at the respective census dates.

A description of the conceptual basis of the estimated resident population is contained in the ABS publication, Population Estimates: Concepts, Sources and Methods (cat. no. 3228.0).